Your hydrometer has three sides. 1. Gravity, 2. Abv, 3. Balling. As you read the gravity, spin it to see the corresponding abv. In your case 1.084 looks like about 12% abv in your OG. Then at 1.001 looks like about 1 or 2%. Your then subtract these two figures to calculate your final ABV. In your case, should be about 10%.
Granted, I'm fairly new to the hobby, but this is how I've come to understand it. If there is anyone here with better explanations, please add.